1. Field of the Invention
This invention relates to photographic light-sensitive silver halide members which are improved in antistatic properties, and more particularly to photographic light-sensitive silver halide members which are improved in antistatic properties without exerting adverse influences on the photographic characteristics of the photographic members.
2. Description of the Prior Art
When photographic light-sensitive members are brought into contact with each other or the surface of a different substance, or stripped during the production or use thereof, electrostatic charges are often accumulated thereon by the contact friction or stripping, because they usually comprise an electrically insulating support and a photographic layer or layers.
These accumulated electrostatic charges give rise to various problems. The most serious problem is that a light-sensitive emulsion layer may be exposed to light by discharge of the electrostatic charges; that is, when a photographic film is developed, dot-like spots, or branch- or feather-like lines, appear therein. These are called "static marks", and significantly reduce the product value of such photographic films. In some cases, the product value is completely lost. It can easily be understood that such static marks appearing, for example, in medical or industrial X-ray films, may lead to a misdiagnosis and inappropriate decision based thereon. This problem is made more troublesome by the fact that the occurrence of such a phenomenon is only revealed by development of the photographic image. Additionally, the accumulated electrostatic charges may give rise to secondary problems, such as that dust is attracted onto the surface of film by the action of the charges, and a uniform coating cannot be obtained.
As described above, the electrostatic charges are often accumulated on the photographic light-sensitive members by the contact friction or stripping during the production or use thereof. In the production process, for example, the contact friction between the photographic film and a roller or the stripping or separation of the emulsion layer from the back side of the support can cause the accumulation of the electrostatic charges. In the case of finished articles, the separation of the emulsion layer from the back side of the support which occurs in winding or exchanging the photographic film, or the stripping due to the contact of, e.g., an X-ray film with mechanical parts in an automatic camera or a fluorescent intensifying screen, may lead to the accumulation of the electrostatic charges. Additionally, electrostatic charges may be caused by contact of the film with wrapping materials.
The static marks induced on the photographic light-sensitive member by the accumulation of electrostatic charges become significant with a raise in the sensitivity of the photographic light-sensitive member and an increase in the processing speed. Recently, the formation of such static marks has become a more severe problem, since photographic light-sensitive members having increased sensitivity have become available and more widely used, and due to the use of high-speed coating, high-speed photographing, high-speed automatic processing, etc.
The best method for overcoming the problems caused by static electricity that has been found is to increase the electrical conductivity, so as to allow electrostatic charges to be dissipated prior to the discharge of accumulated electrostatic charges.
Therefore, a method of increasing the electrical conductivity of a support for use in photographic light-sensitive members or of various coated surface layers has heretofore been studied, and attempts have been made to utilize various hygroscopic substances and water-soluble inorganic salts, certain surface active agents, polymers, etc. For example, polymers as described in U.S. Pat. Nos. 2,882,157, 2,972,535, 3,062,785, 3,262,807, 3,514,291, 3,615,531, 3,753,716, 3,938,999, etc., surface active agents as described in U.S. Pat. Nos. 2,982,651, 3,428,456, 3,457,076, 3,454,625, 3,552,972, 3,655,387, etc., zinc oxide, semiconductors, colloidal silica, etc., as described in U.S. Pat. Nos. 3,062,700, 3,245,833, 3,525,621, etc., are known.
Many of these substances, however, vary in capability depending upon the type of the support and the photographic composition; that is, when they are used in certain specific film supports, photographic emulsions, or other photographic elements, good results can be used, while when used in other film supports or photographic elements, they not only have no antistatic capability, but also exert adverse influences on the photographic characteristics.
In particular, it is difficult to prevent the hydrophilic colloidal layer from becoming charged; particularly, the reduction in the surface resistance at low humidities is not sufficient, and the problem of adhesion between the photographic light-sensitive members themselves or between the photographic light-sensitive members and other substances at high temperatures and humidities often occurs.
Furthermore, the above-described substances often cannot be used because they exert adverse influences on the photographic characteristics, such as the sensitivity of a photographic emulsion, fog, granularity, image sharpness, etc., or yield the scum in a fixer, even though they may have an excellent antistatic effect. For example, while it is generally known that polyethyleneoxide based compounds have an antistatic effect, they often exert adverse influences on photographic characteristics, such as an increase in fog, desensitization, deterioration in granularity, etc. In particular, it has been difficult to impart the desired antistatic properties to light-sensitive members comprising a support and photographic emulsions coated on both sides of the support, such as medical direct X-ray light-sensitive members, without exerting adverse influences on the photographic characteristics thereof.